1. Field of the Invention
The present invention relates to a vibration gyroscope which can be used for a navigation system that gives an appropriate guide by detecting a rotation angular velocity to detect the position of a moving object, or used for an anti-vibration system, such as a camera-shake prevention apparatus that correctly prevents a shake by detecting a rotation angular velocity due to external vibration, such as camera shake.
2. Description of the Related Art
The configuration of a conventional vibration gyroscope will be described by referring to FIGS. 6 and 7.
In the figures, a vibration gyroscope 31 includes a vibrator 32. The vibrator 32 is formed in a regular triangular prism shape by, for example, permanently elastic metal materials, such as elinvar, and materials generating mechanical vibration, such as quartz, glass, crystal, and ceramic. Piezoelectric elements 33 and 34 for driving and detection are provided at side faces adjacent to each other, and a feedback piezoelectric element 35 is provided at the other side face. The piezoelectric elements 33 to 35 are made by providing boards made from piezoelectric members with electrodes on both surfaces, although they are not shown in detail. Near a node of the vibrator 32 and on the ridgeline located between the piezoelectric elements 33 and 34, the middle sections of two support pins 36 serving as support members are mounted. The support pins 36 are made of metal wire formed in a gate shape. Both ends of the support pins 36 are inserted into first insertion holes 38 provided for a mounting substrate 37 and secured by solder or the like. The mounting substrate 37 is made by molding a plane plate from, for example, glass epoxy, and by providing the first insertion holes 38 and a second insertion hole 39 both penetrating the two main surfaces. The second insertion hole 39 is formed more outward than the first insertion holes 38 on the main surfaces of the mounting substrate 37. Opposing the mounting substrate 37, a support substrate 40 is disposed. The support substrate 40 is made by injection molding a plane plate from a metal, such as nickel. In the support substrate 40, a protrusion 41 is perpendicularly extended from one main surface, and a convex section 43 is formed for positioning the mounting substrate 37 on the surface of section 43 in the vicinity of the protrusion 41. In addition, at four corners on the other main surface, hook-shaped legs 42 are provided in order to engage the vibration gyroscope with other members. The protrusion 41 of the support substrate 40 is inserted into the second insertion hole 39 of the mounting substrate 37 and secured by solder or the like, and the mounting substrate 37 is supported by the convex molded section 43. Therefore, the mounting substrate 37 and the support substrate 40 are secured through a gap 44 while they oppose each other.
Since the gap 44 is provided between the mounting substrate 37 and the support substrate 40 in the vibration gyroscope 31, vibration transferred to the mounting substrate 37 from the vibrator 32 through the support pins 36 is prevented from transferring to the support substrate 40.
Another conventional vibration gyroscope will be described below by referring to FIG. 8. Portions which are the same as or corresponding to those shown in FIG. 6 are indicated by the same symbols and the descriptions thereof are omitted.
In a vibration gyroscope 51 shown in FIG. 8, a support substrate 52 and a mounting substrate 53 are not provided with a protrusion or a second insertion hole. Both the substrates 52 and 53 are combined with adhesive or the like through a cushion plate 54 which is made by molding an elastic member, such as butyl rubber, into a plane plate. Since the cushion plate 54 absorbs vibration, vibration transferred to the mounting substrate 53 from the vibrator 32 through the support pins 36 is suppressed.
The conventional vibration gyroscopes have the following problems.
In the vibration gyroscope 31, vibration to be transferred from the mounting substrate 37 to the support substrate 40 can be suppressed. However, vibration transferred from the vibrator 32 to the mounting substrate 37 cannot be suppressed, and vibration leakage from the vibrator 32 cannot be sufficiently reduced. As a result, vibration in the vibrator 32 is not stable and the characteristics of the vibration gyroscope may deteriorate.
In the vibration gyroscope 51, vibration to be transferred from the vibrator 32 to the mounting substrate 53 can be suppressed by the cushion plate 54. Since the cushion plate 54 is an independent member, assembly work becomes complicated.